1. Field of the Invention
This invention relates to thermometers for the measurement of human body temperature, and specifically to disposable types.
2. Description of the Prior Art
Patients in hospitals and other health care environments routinely have their temperatures taken as a diagnostic procedure. The number of temperatures taken per year, in the United States alone, number approximately 3 billion. This need, in the past, has been served by the Mercury Thermometer and, to some extent, more recently by Electronic Thermometers with both disposable and non-disposable probes.
All thermometers require sterilization after each use, or that a portion of the device which contacts the patient be disposable.
Mercury thermometers are too expensive for disposal after each use and require sterilization. The alcohol dip sterilization, which has been used in the past, is relatively convenient but has proven to be inadequate and results in patient cross-contamination. Other methods are time consuming and expensive. The mercury thermometer has a very long 3 minute response time which results in an inefficient nurse-administration pattern. The mercury thermometer is, in addition, fragile and hazardous should the component parts be ingested. The electronic thermometer with disposable probes overcomes the problem of cross-contamination and represents a significant step forward. The main limitation to this time has been the response time. Although faster than the mercury type, typical examples are 20 seconds or greater. Because of the bulk of the measuring device, the nurse is required to hold the probe in the patients mouth or immediately supervise its use, and therefore results in no improvement in the nurse-utilization procedure. The slowness of the disposable electronic types result because of the basic implementation of the device. The temperature-sensitive portion of the probe (a Thermistor, Thermocouple, or other heat-sensitive element) is too expensive to discard with each use and is therefore shrouded with a disposable cover. The covers are either a thin plastic which is a relatively poor conductor of heat, or a thicker plastic with a thermally conductive metal insert which exhibits a large thermal mass. Either of these types results in response times of 20 seconds or greater.